What your user-agent says about you, from the shell — plus why UA rotation alone does nothing https://quanticdata.io/tools/user-agent/

qd-ua.sh

#!/usr/bin/env bash
# What a server actually sees, and why rotating the user-agent alone changes nothing.
#
#   ./qd-ua.sh                      # your current UA, parsed
#   ./qd-ua.sh "Mozilla/5.0 (…)"    # parse any UA string
#
# Interactive lookup: https://quanticdata.io/tools/user-agent/
set -euo pipefail

ECHO_SERVICE="${ECHO_SERVICE:-https://httpbin.org}"

# The echo service is a convenience, not a dependency — everything below still
# works if it is down, which public echo endpoints regularly are.
echo_json() {
  curl -sS -m 15 "$@" 2>/dev/null | jq . 2>/dev/null
}

UA="${1:-$(echo_json "$ECHO_SERVICE/user-agent" | jq -r '."user-agent" // empty' || true)}"
UA="${UA:-$(curl --version | head -1 | awk '{print "curl/"$2}')}"

echo "user-agent"
echo "  $UA"
echo

echo "what a server reads out of it"
case "$UA" in
  *Chrome/*)  printf "  browser   Chrome %s\n" "$(sed -n 's/.*Chrome\/\([0-9.]*\).*/\1/p' <<<"$UA")" ;;
  *Firefox/*) printf "  browser   Firefox %s\n" "$(sed -n 's/.*Firefox\/\([0-9.]*\).*/\1/p' <<<"$UA")" ;;
  *Safari/*)  echo "  browser   Safari" ;;
  *curl/*)    echo "  browser   curl — this is not a browser and every anti-bot vendor knows it" ;;
  *python*|*requests*) echo "  browser   a Python client, announcing itself" ;;
  *)          echo "  browser   unrecognised" ;;
esac
case "$UA" in
  *Windows*) echo "  platform  Windows" ;;
  *Macintosh*|*"Mac OS X"*) echo "  platform  macOS" ;;
  *Android*) echo "  platform  Android" ;;
  *iPhone*|*iPad*) echo "  platform  iOS" ;;
  *Linux*)   echo "  platform  Linux" ;;
esac
case "$UA" in
  *Mobile*) echo "  form      mobile" ;;
  *)        echo "  form      desktop" ;;
esac

echo
echo "everything else the server sees"
# `|| true` matters: under `set -e` a failed substitution would end the script.
HEADERS=$(echo_json "$ECHO_SERVICE/headers" -H "User-Agent: $UA") || true
if [ -n "$HEADERS" ]; then
  printf '%s' "$HEADERS" | jq -r '.headers | to_entries[] | "  \(.key): \(.value)"'
else
  echo "  ($ECHO_SERVICE is not answering — set ECHO_SERVICE to another echo endpoint)"
fi

cat <<'NOTE'

Rotating the user-agent alone accomplishes nothing. A server fingerprints the whole
request: header ORDER, the TLS/JA3 handshake, HTTP/2 settings frames, and whether the
sec-ch-ua hints agree with the UA string. A Chrome 140 user-agent arriving with
Python's TLS signature and no client hints is MORE distinctive than plain curl.

Coherence is the point:
  - mobile exit IP  -> mobile user-agent AND sec-ch-ua-mobile: ?1
  - German exit     -> Accept-Language starting with de
  - Chrome UA       -> Chrome's header order and TLS fingerprint

That last one is not something you can set from curl. It is what
https://quanticdata.io/web-scraping-api/ does for you server-side.

UA lookup: https://quanticdata.io/tools/user-agent/
NOTE